Ka spot beam satellite systems and inroute links are subject to noise floor variations as a function of frequency. The variations are mainly due, but not limited to, self-interference effects caused by a satellite gateway's outroute transmissions. The inroute noise floor spectrum has pedestal and valley-like variations over a frequency range. Satellite terminals that range in areas having a relatively low noise floor may not have sufficient energy to establish a link on an inroute in areas having a relatively high noise floor. If a link can be established, errors may occur during a time interval in which a satellite terminal is adjusting its power level.
Automatic gain control subsystems typically compute received power on a continuous burst-by-burst basis without any distinction as to underlying signal characteristics such as, for example, an operating code rate. Transmit power is proportional to the code rate. Consequently, averaging received power levels forces the automatic gain control subsystems to settle to an automatic gain control value proportional to a distribution of inroutes with varying code rates. When most inroutes are operating in clear sky conditions, the automatic gain control value will settle to a highest code rate power level. Centering the automatic gain control value at the highest code rate power level negatively affects inroute bursts received in a faded condition at lower code rates. As an example, if the automatic gain control value for an inroute settled to a power value associated with a code rate of 9/10, a burst received at a code rate of 1/2 would experience packet loss and degradation due to a limited dynamic range of a demodulator.